overhaul to use node-fetch internals

classes/caching/memory_cache.js

@@ -1,5 +1,15 @@
+import { Readable } from 'stream';
 import { KeyTimeout } from './key_timeout.js';
 
+function streamToBuffer(stream) {
+  const chunks = [];
+  return new Promise((resolve, reject) => {
+    stream.on('data', (chunk) => chunks.push(Buffer.from(chunk)));
+    stream.on('error', (err) => reject(err));
+    stream.on('end', () => resolve(Buffer.concat(chunks)));
+  });
+}
+
 export class MemoryCache {
   constructor(options = {}) {
     this.ttl = options.ttl;
@@ -8,7 +18,15 @@ export class MemoryCache {
   }
 
   get(key) {
-    return this.cache[key];
+    const cachedValue = this.cache[key];
+    if (cachedValue) {
+      return {
+        bodyStream: Readable.from(cachedValue.bodyBuffer),
+        metaData: cachedValue.metaData,
+      };
+    }
+
+    return undefined;
   }
 
   remove(key) {
@@ -16,8 +34,9 @@ export class MemoryCache {
     delete this.cache[key];
   }
 
-  set(key, value) {
-    this.cache[key] = value;
+  async set(key, bodyStream, metaData) {
+    const bodyBuffer = await streamToBuffer(bodyStream);
+    this.cache[key] = { bodyBuffer, metaData };
 
     if (typeof this.ttl === 'number') {
       this.keyTimeout.updateTimeout(key, this.ttl, () => this.remove(key));